1. Field of the Invention
The present invention relates generally to a stereoscopic (3-D) display capable of viewing a stereoscopic image without using special glasses, and more particularly, to an indicator for teaching to a viewer the position where a stereoscopic image can be viewed.
2. Description of the Prior Art
A stereoscopic display capable of viewing a stereoscopic image without using special glasses has been conventionally known. In the stereoscopic display, a parallax barrier, a lenticulated lens, and the like are arranged on the side of a viewer of a display screen of a display panel such as a liquid crystal display panel. Consequently, the stereoscopic display separates light beams from a left eye image and a right eye image which are displayed on the display panel into left image light beams and right image light beams and supplies the left image light beams and the right image light beams to the viewer. The viewer views a stereoscopic image.
FIG. 28 is a diagram showing the principle of a stereoscopic display capable of viewing a stereoscopic image without using special glasses using a parallax barrier. The stereoscopic display is constituted by a back light 1, a liquid crystal display panel 2, and a parallax barrier 3. In the liquid crystal display panel 2, vertical columns of left eye pixels L and vertical columns of right eye pixels R are alternately formed. In the parallax barrier 3, a lot of slits 3a and light shading portions 3b which extend in the vertical direction are alternately formed. There is sufficient binocular parallax for a human being to perceive a stereoscopic image between a left eye image composed of the left eye pixels L and a right eye image composed of the right eye pixels R.
In the stereoscopic display, when light beams emitted from the back light 1 pass through the liquid crystal display panel 2, the light beams passing through the left eye pixels L become left eye image light beams 4L upon being modulated by left eye image information, and the light beams passing through the right eye pixels R become right eye image light beams 4R upon being modulated by right eye image information. The left eye image light beams 4L and the right eye image light beams 4R reach the viewer upon being laterally separated by the parallax barrier 3. The viewer who desires to view a stereoscopic image puts his or her head in a predetermined position. The left eye image light beams 4L are incident on the left eye 5L of the viewer through the slits 3a. The right eye image light beams 4R are incident on the right eye 5R of the viewer through the slits 3a. Consequently, the viewer can recognize a stereoscopic image by the above-mentioned binocular parallax. The predetermined position where the viewer can recognize a stereoscopic image is taken as a stereoscopic view position. At this time, the right eye image light beams 4R are not incident on the left eye 5L of the viewer upon being intercepted by the light shading portions 3b. The left eye image light beams 4L are not either incident on the right eye 5R of the view upon being intercepted by the light shading portions 3b.
In the stereoscopic display, when the head of the viewer is positioned outside the stereoscopic view position, the right eye image light beams 4R are incident on the left eye 5L of the viewer, and the left eye image light beams 4L are incident on the right eye 5R of the viewer. Consequently, the viewer cannot recognize a good stereoscopic image. The above-mentioned position is taken as a pseudo-stereoscopic view position.
In order to enjoy a stereoscopic image, therefore, the viewer must first find out a stereoscopic view position where a good stereoscopic image can be viewed and fix his or her head in the position. When the head deviates from the stereoscopic view position while the stereoscopic image is being enjoyed, the head must be put in the stereoscopic view position again.